1
KNH 411
IntakeMeasured in kilojoules (kJ) or kilocalories (kcal) -
food energyDetermined by bomb calorimeterNutrition Facts label, food composition tables,
dietary analysis software
24-Hour Energy Expenditure (EE)Resting energy expenditure (REE)Thermic effect of foodPhysical activity
Resting energy expenditure (REE)Sustain life, keep vital organs functioning60-75% of EE, 1 kcal/kg body wt./hr factors affecting REE
Lean body massMale sexBody temperatureAgeEnergy restrictionGenetics
Basal energy expenditure (BEE)
Difficult to measure
Thermic effect of food (TEF)Measured for several hours postprandialDigest, absorb, metabolize, store, and eliminate
nutrients 10% of EE
Physical Activity EEMost variable20-25% of EE Influenced by body weight, number of muscle groups
used, intensity, duration and frequency of activity
MethodsEquations Indirect calorimetryDoubly-labeled waterDirect calorimetry
Equations for estimating EEHarris-Benedict made in 1900’s WHO IOM DRI – estimated energy requirement (EER)
Includes physical activity (PA) coefficient Separate calculations for overweight adults and
overweight children and adolescents – based on BMI
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Indirect CalorimetryMetabolic research or critically ill patientsMeasures inspired and expired air by minute
ventilationEE proportional to oxygen consumption and carbon
dioxide production
Doubly Labeled Water “Gold standard” 2 stable isotope forms of water Rate at which isotopes disappear is measured in
urine over 2-week period
Direct CalorimetryChamber which measures heat expired through
evaporation, convection, and radiationRarely available
Interaction of nervous and endocrine systemsOrexigenicAnorexigenicAdaptive thermogenesis
Appetite stimulated by hypothalamusSecretions of pancreatic and GI hormones Increase and decrease appetite and food intakePradar-Willi syndrome
Hormones affecting appetite & food intake InsulinGlucagonAmylin decreases appetiteCholecystokinin (CCK) hormones; decrease
appetiteGlucagon like peptide-1 hormones; decrease
appetitePeptide YY hormones; decrease appetite Ghrelin
Adipocyte – fat cell; mostly TG
Storage site - 90% energy reserves
Other functions
White fat (WAT) vs. brown fat (BAT)
Lipogenesis
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Adiponectin and leptin stimulate storage
Hypertrophy and hyperplasia of cells
“Adiposity rebound”
“Two compartment model” – fat vs. fat-free mass
Use of height and weight – BMI commonly used to assess obesityDoes not directly measure fatnessClinical judgment should be used
Body Mass Index (BMI)Obese ≥ 30
calculation and classifications
BMI percentiles CDC growth chartsPediatric population≥ 95%th percentile = obesity≥ 85%th percentile = overweight
Important predictor of health status
Abdominal/central body fatApple, android
Lower body fatHips and thighs, pear, gynoid
Measured by waist circumference and waist-to-hip ratio
Waist circumference Increased risk of type 2 DM, htn., dyslipidemia,
CHD, metabolic syndrome> 40 in. males, > 35 in. females – “high risk”
Waist-to-hip ratio (WHR)Waist circumference/hip circumferenceDisease risk increases with WHR > 0.95 in males
and >0.8 in females
Key concept: fat deep within abdomen and around intestines and liver increases disease risk
“Globesity,” “epidemic”
In the U.S. - NHANES dataSignificant increases
Canada
Europe: 45-80% of population
By race, ethnicity, SES, age
“The age of caloric anxiety”
Type 2 diabetes
High blood pressure
CHD
Cancer
Mortality
Chronic energy intake exceeding energy expenditure
Key contributors:Medical disorders and treatmentGeneticsObesigenic environment
Medical disorders and treatmentCushings syndrome, hypothyroidism, Prader-WilliPharmacological agentsSmoking cessationNight eating syndromeBinge eating
Genetics 40-50% of BMI explained by genetics Influences taste, appetite, intake, expenditure, NEAT,
storage “Set-point” theoryMultiple genes Predictive in families – parents & twins
80% of offspring with 2 obese parents 40% of offspring with 1 obese parent MZ twins more likely than DZ twins
Obesigenic environment “Toxic food environment” – convenient availability of
low-cost, tasty, energy-dense foods in large portionsEvidence supports low-energy-dense foods for satiety
Soups, fruits, vegetables, cooked whole grains Barriers – cost and convenience
Two-step processAssessmentManagement
NIH algorithm for treatment
© 2007 Thomson - Wadsworth
AssessmentBMI & waist circumferenceCurrent chronic diseasesDiet and physical activity habitsPatient’s readiness to lose weight Identify and address barriers, coping skills, self-
efficacyBehavioral assessment
ManagementUse of recommended therapiesControl of factors known to increase risk of morbidityTherapies include – diet, physical activity, behavioral
therapy, bariatric surgery, pharmacologic treatmentLose 10% in 6 mo.
Nutrition therapyReduce intake 500-1000 kcal/d.Lose 1-2 lbs./weekNIH low-kcalorie diet Minimize CVD risk factors – NCEP Therapeutic
Lifestyle Changes diet1000-1200 kcal/d women, 1200-1600 kcal/d men
minimumUnclear whether altering macronutrient levels is
beneficial
© 2007 Thomson - Wadsworth
Physical ActivityCrucial for weight maintenanceMinimum 30-45 min moderate activity 3-5 days/week Initiate slowly and graduallyCan be programmed or lifestyle activities
Behavior TherapyTechniques for identifying and overcoming barriers
Self-monitoring Stimulus control Rewards
Pharmacologic TreatmentBMI ≥ 30 or ≥ 27 with risk factorsConsider cost and side effects, and rebound weight
gainLong-term use
Sibutramine (Meridia) Orlistat (Xenical)
Others for short-term use
SurgeryBariatric surgery – BMI ≥ 40 or ≥ 35 with risk factorsRoux-en Y gastric bypass, vertical banded
gastroplasty, adjustable band gastroplastyAssess benefits vs. risksPreoperative screening & education important